Pressure medium drive for electric switches



United States Patent PRESSURE MEDIUM DRIVE FOR ELECTRIC SWITCHES 10 Claims, 3 Drawing Figs.

U.S. Cl 137/59615, 137/459, 4/29 Int. Cl. F16k 11/10 F 16k I I/24 Field of Search 137/459,

3,151,455 10/1964 Tennis .I. l37/596.l5X

Primary Examiner-Henry T. Klinksiek Attorneys-Curt M. Avery, Arthur E. Wilfond, Herbert L.

Lerner and Daniel J. Tick ABSTRACT: In a pressure medium drive for electric switches there is provided a valve which, inv response to an actuating command, is opened and remains'open until it is closed by the flow of pressure medium theretlirough. The valve has associated therewith a cylinder and a piston which actuate the valve with the aid of the pressure medium. The cylinder is connected at two locations to the flow path of the pressure medium through the valve. Insert means located between the two locations of the flow path and having a throttling bore produce a pressure difference between the locations.

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PRESSURE MEDIUM DRIVE FOR ELECTRIC SWITCHES Our invention relates to pressure medium drive for electric switches.

in pressure medium drives for electric switches, the valve through which the pressure medium flows into the drive cylinder wherein a drive piston is displaceable must remain open long enough so that the switching action is fully completed with reliability. lf the valve is open for too short a period which can occur, for example, because of a so-called tip-command" (Tippkommando), it can cause the switch to remain in an intermediate setting between the on and the off switching positions. This could cause extensive damage.

In compressed air drives it is known to keep the valve open pneumatically, when actuating the valve, by filling a space with compressed air which can escape only relatively slowly through a small opening. The compressed air in this space ensures that the valve will be open a sufficiently lengthy period independently of the duration of the opening command. The known system is not readily usable, however, for other pressure media than compressed air which, like hydraulic liquids, for example, are practically incompressible and are used with a many-times higher pressure of 100 atmospheres or more. Furthermore, a marked disadvantage can be presented by the known system in that it affords only a specific time interval during which the valve is open and not an interval which is dependent on the actual duration of the switching action.

It is accordingly an object of our invention to provide pressure medium drive for electric switches with a valve which is opened by a preferably electrical actuating command and remains open until it is closedby the termination of the flow of 7 pressure medium therethrough.

It is a further object of our invention to provide such drive which will avoid the aforementioned, disadvantages of the known drives of this general type.

With the foregoing and other objects in view. we provide in accordance with our invention a cylinder and a piston which actuate the valve with the aid of the pressure medium. The cylinder is connected at two locations to the flow path'of the pressure medium through the valve. lnsert means located between the two locations of the flow path produce a pressure difference between the locations.

In accordance with a further feature of our invention. the pressure difference arising with the flow of pressure medium in the valve is used for actuating the valve. Thereby, without any auxiliary energy, the valve is kept open for a time interval which conforms or is adjusted to the flow of the pressure medium and which is substantially identical with the duration ofthe switching action.

In accordance with other features of our invention, flow resistance means are provided between both positions of the flow path and upstream of the valve plate of the piston. The flow resistance means can be a spring-biased piston forming a throttling station in the flow path of the pressure medium. The piston can be used directly as control slider for the pressure medium serving to actuate the valve. The piston is advantageously rotationally symmetrical and is provided with a throttling main bore and an annular groove formed in the outer surface thereof, both having an axis coinciding with the axis of symmetry of the piston. The annular groove communicates with suitable channels formed in the wall of a cylinder related thereto.

In accordance with another embodiment of the invention, there is provided a nozzle member having a tapered main bore and provided with radial bores at the portion thereof having the smallest nozzle across section. The valve cylinder is connected to the portion of nozzle member having the smallest cross section.

In accordance with a further feature of the invention, the controlled valve can, for its part, be used as a control valve for a valve actuated by the pressure medium, whereby greater adjusting forces are produced.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in pressure medium drive for electric switches, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method ofoperation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with'the aecompanying drawings, in which:

FIG. 1 is a sectional view of a valve and a control system associated therewith for hydraulic drives for electric switches, constructed in accordance with our invention;

FIG. 2 is an enlarged view of a fragment of thevalve and system of FIG. 1. showing the throttling member in a different phase from that shown in FIG. I; and.

FIG. 3 is a sectional view of another embodiment of the valve and controlsystem shown in FIG. l.

in the interest of clarity and to avoid encumbering the drawings with known structural details, such members as the hydraulic storage source, the drive cylinder, the drive piston andthe sump as well as the switch which is to be actuated have been omitted from the drawings.

Referring now to the drawings and'first, particularly, to FIG. 1 thereof. there is shown an arrow 1 indicating the direction of flow of a pressure medium from a nonillustrated hydraulic storage source. A double-headed arrow 2 represents the connection to a drive cylinder, and an arrow 3 indicates flow through a duct to a low-pressure system or sump.

In the embodiment of FIG. 1. there is provided a valve 4 which has a valve plate 5 which. due to the biasing action of a spring 6, normally closes a valve seat 7. The valve plate 5 is connected by a plunger or tappet 8 with an actuating piston 9.

The piston 9 is displaccable in a cylinder l2'which is in communication with a control valve 13 at the end of the cylinder 12 that faces away from or is more remote from the valve plate 5. The control valve 13 is connected by a duct 14 with the nonillustrated hyraulic reservoir from which pressure medium flows in the direction of the arrow 1. The control valve 13 includes a spherical member or ball 15. which abuts a valve seat 17 under the biasing force of a spring 16 so as to close the valve 13, and a tappet 18 which is displaceable into engagement with the ball 15 for forcing the ball, against the biasing action of the spring 16, away from the seat 17 so as to thereby open the valve 13- The tappet 18- is located at the end of an armature of an electromagnet 20 which is secured by screws or the like at 21 to the housing 22 of the control valve 13. The tappet 18 is coordinated with a piston 25 which has a conical valve plate 26 that is engageable with a'correspondingly conical valve seat 27 provided at an end of a cylinder chamber 27' formed in the housing 22, so as to thereby close the. valve 13 at the seat 27 when the tappet 18 raises the ball 15 from the valve seat 17 and therebyopens the valve 13' at the seat 17.

A cylinder 30 is additionally provided in the housing 22. A rotationally symmetrical piston 31 is seated in the cylinder 30 and is formed with a flange 32 which abuts a projection 33 when only the biasing force of a spring 34 is exerted thereon. The piston 31, as seen in F IG. 1, as well as in the enlarged view thereof in FIG. 2, is formed with a through bore tapered at an end thereof facing the tappet 8. The portion of this tapered or throttling bore having the narrowest cross section is indicated by thereference numeral 35.

An annular groove 37 'is provided in the outer surface of the piston 31 so as to permit the piston 31 to act as a control slide. The annular groove 37 connects two ducts 38 and 39'as shown in FIG. 1. The duct 38. extends to the end of the piston'25 or cylinder 27' that faces away from the control valve 13. The duct 39 is connected to a duct 40 which, in turn, connects an annular space 43 at the piston 9 with a return flow line, represented. by the arrow 3, to the nonillustrated sump.

Furthermore; the duct39 isconnected by aduct 44 with the end ,of the piston 25 or cylinder 27' facing the control valve There is further located inthe housing 22 an elongated valve plate 50, acting'as an hydraulic switch, which abuts a valve seat 52 under the biasing force of a spring 51. The endof the valve plate 50 facing away from the valve'seat 52and whichis connected by a duct 54 with thecylinder 12, has a greater cross-sectional area than the 'cross-sectionalarea of the end thereof encircled by the seat '521 The valve plate 50 canaccordinglyact as a differential piston.

, 63 is disposed in a'chamber 65 which is connected by a duct with a source of pressure medium flowing in the direction, of.the;arrow l. r

The valve plate annular space 70 surrounding the tappet 67' constitutesv the 7 outlet end of the valve 61, which is bounded at the right-hand The magnet 20 is energized in order to open the valve 4. ,1 When electrically energized, the electromagnet'coils of the magnet 20 force the armature located therewithin toward the left-hand side of FIG. 1 so that the tappet 18 strikes the ball and moves it toward the left-hand side of FIG. 1 away from the i a valve seat 17; Pressure medium in'the .duct 14 and the chamber. located to the left-hand side of the ball 15 then passes into the cylinder 12 from the valve l3and simultaneously through the duct 54 to the valve plate 50. The piston 9 is f .va lve plate. 62. The valve 80 includes a ball 81, which abuts a valve seat 83 under the biasing force. of a spring 82 so as to then displaced downwardly, as viewed in FIG. 1, under the, ac-

moved away from theseat 7, opening a path for the flow of pressure medium inthe direction of the arrow 1 past the seat 7, through the tapered or throttling bore 35, and in the tion of the pressure medium, and the valve plate 5 is thus,

side thereof, as viewed in FIG.3, by a piston 7l. The outlet 70 leads to a nozzle member 72' of the shape shown in FIG. 3.

. As can be seen from FIG.3, the nozzle member 72has a ,7 tapered main bore, and radial bores74 are formed in the noz- ,zle member 72 at a portionthereof having the narrowest main bore diameter. An annular channel 75. is forined on the exteri- I ;orfof the nozzle member 72 into which the radial bore 74 open. The portion 76 of the nozzle member 72 having the. wider main bore diameter leads in the direction of the arrow 2 to' a nonillustrated drive cylinder wherein a piston for actuating an electriccircuit is disposed.

"A valve 80 is connected to the chamber 65 upstream of the close the valve 80. A tappet 85, provided with a portion 86 of t enlarged diameter, engages the ball 81.;The enlarged diameter downward direction represented by the arrow 2 to a nonillus- I i trated drive cylinder. The duct leading tojthe nonillustrated sump in the direction of the arrow 3is kept closed due to the differential piston action of the valve plate 50.

- The throttling bore presents resistance todthe tlowof pressure medium to the nonillustrated drive cylinder and'acts as a sensing member for the flow. A pressure drop exists at the piston 31 due ,to the passage of the pressure medium through the throttling bore 35. The pressure difference causes the piston 31 to be shifted to the right-hand side of FIG. 1 against the biasing forccof the spring 34 andto the position shown in the enlarged fragmentary view of FIG. 2. Thereby the duct 38 is exposed to the pressure medium. flowing toward the drive cylinder. Pressure medium consequently passes through the duct 38 to the end of the piston 25 or cylinder 27? facing away from the control valve 13. Consequently. the tappet l8 keeps, the ball 15 away from the seat 17 so that the valve 13 remains open'even if the magnet 20 were prematurely deenergizedf Accordingly, due to the flow of pressure medium through the open valve 13 to the cylinder12, the valve4 is therefore also kept open. I I

At theend of the control stroke, when the nonillustrated drive piston reaches its limiting position, the pressure medium .flows stops. The pressure drop at the piston 31 becomes zero,'

and the spring 34 can therefore again force the piston 31 to its furthermost left-hand position asshown in FIG.'1. The duct 38 is thereby connected to the duct 39, and the piston 25 is re- 1 lieved of the pressure previously exerted by the pressure medium so that the spring 16 forces the ball 15 against the seat 17,

thereby closing the control valve 13. The piston 25 which then travels toward the right-handside of HO. 1, accordingly raises the conical valve plate 26 from the corresponding seat 27 so as to thereby connect the cylinder 12 through the duct 44 with the duct 39. Accordingly, pressure medium contained in the portion 86 acts as a control slider. The lower edge, 87 thereof,

as viewed in FIG. 3, islocated about 0.5 mm. above the side 88 of a lateral slot 89 formed in thehous ing 60. The enlarged diameter portion 86 of the tappet 85 is engageable by a tappet 90 which is displaceable downwardly, as viewed in FIG. 3, by adouble-armed lever 92 pivotable about pivot 91, when the;

lever 92 is actuated by a tappet 93 cooperating with anarmaturc of an electromagnet94;

A pin 96 is secured in the lever 92 and abuts a cylindrical I b A transverse channel 106 is formed in'thevalve housing Thetransverse channel 106, by meansof the duct 107, connects the portion of the space 100 located beneath the cylinf;

drical member 103, as viewed in FIG. 3, with a duct 108 which communicates with the o'utlet 109 of the control valve, and

communicates through the channel 110 with the gap formed by the slot 89 between the enlarged portion 86 and the upper surface of the wall 88 The slot 89 isconnected through the' bore 111 with the space 112 whereinthe double-armedlever 92 ispivotally mounted,and through-thebore 114 with a nonillustrated low-pressure vessel of the hydraulic system, in the direction of the arrow 3. Furthermore, the portion of the cylinder 69facing away from the valve plate 62 is connected to the transverse channel 106 through-a duct 105. A duct 113 connects the annular channel 75 with the space 98.

cylinder 12 can pass through the ducts 39 and 40 to the nonil-- lustrated sump in the direction of the arrow 3. The spring 6, at-

this time, closes the valve 4.

As can be seen, the valve 4 remains open without applying any external auxiliary energy, after a command to open has To open the valve 61, the electromagnet 94 is energized.

The electromagnet' 94, by the actuation, of the armature thereof, which acts serially on the tappet 93, the lever 92, the tappet 90 and the tappet 85, forces open the control valve80. As the valve 80 is opened, the outlet through slot 89 is closed by the enlarged portion 86 of the tappet 85. Consequently, the pressure medium flows through the duct 108 and the channel 106 aswell'as the duct 105 to the right-hand side of the piston 1 6:8, as viewed in FIG. 3, and forces the valve 61 to the leftbeen given to the tappet l8, justso long as pressure medium matically closes. The components required for effecting this control are integrally constructed with the'valve 4 so that a closed, relatively easily mountable block is produced.

, flows therethrough and produces a specific pressure drop at a a the piston 31. If this is no longer thecase, the valve 4 autohand side of FIG. 3 into the open positionthereof. Simultaneously, pressure medium from thehcontro'l valve passes through the duct 106 to the lowerend of' the cylindrical member 103, as viewedin FIG. 3,

The cylindrical piston member 103 isforced upwardly, as

. viewed in FIG. 3, by pressure mediumcoming fromthe con- The embodiment of the invention shown in FIG5 3 includes a housing 60, wherein a valve .61, formed of a valve plate 62, a

biasing spring 63 and avalve seat 64, is mountedw-Thespring trol valve 80, because the pressure applied downwardlyto the upper end of the cylindrical member103 is lower than that applied upwardly to the lower end thereof. Only static pressure 62 is connected through atappet 67 with a piston 68'which is slidably displaceable. in a cylinder 69. An

reduced by the flow in the nozzle member 76 and appearing at the narrowest location 73 of the nozzle member 72 acts on the upper end of the cylindrical member 103, namely through the ducts 99 and 113. Therefore, the cylindrical member 103 moves the double-armed lever 92 in a counterclockwise direction by means of the pin 104 so that the other end of the lever 92 forces the pin 90 downwardly. An hydraulic automatic or self-holding action then takes place, which retains the control valve 80 in open position.

The pressure on the cylindrical member 103 is given by the pressure difference between the accumulated pressure existing in front of the valve seat 64 and the pressure in the nozzle member 72 reduced by the flow. The pressure difference attained with an embodiment having the aforedescribed nozzle member as sensing member, was about atmospheres at an operating pressure of 200 atmospheres. This is sufficient by far to keep the valve 61 open with a degree of certainty. The pressure difference varies with the nozzles cross section. because the latter influences or effects the flow velocity.

When the drive controlled by the valve has reached its end position, however, the aforementioned pressure difference becomes zero. The pressure in the vicinity of the bores 74 down stream from the valve plate 62 then adjusts to substantially the same pressure that exists upstream of the valve plate 62. This pressure is transmitted through the channels 113 and 99 also into the space I00. In this case, the piston 103 does not exert any force in a counterclockwise direction on the lever 92. On the contrary, the pin 97 then acts as a piston. The cylindrical member 103 and the pin 97 together constitute a differential piston which turns the lever 92 clockwise through the pin 96 under the action of the pressure prevailing in the space 98. The spring 82 can thereby close the control valve 80. With the upward motion of the tappet 85, as shown in FIG. 3. the outlet through the slot 82 is simultaneously freed from the enlarged diameter portion 86 so that the transverse channel 106 is evacuated. Therefore, the valve 61 closes under the biasing action of the spring 63 as soon as the flow of pressure medium through the nozzle member 72 ceases.

ln tests conducted by us or at our direction, the valve embodiment shown in FIG. 3 has proven to be outstanding. As can be seen, no auxiliary energy is required for actuating the valve, and the valve remains open only as long as necessary to complete the switching action. Also, the valve of our invention requires astoundingly brief periods of several milliseconds for opening thereof. Also, the time interval necessary for closing the valve is only a few milliseconds. Thus, the valve of our invention is opened as long as necessary independently of the command interval, but only as long as necessary.

We claim:

1. In a pressure medium drive for electric switches. means defining a pressure medium flow path, valve means in said flow path openable and remaining open in response to an actuating command until closed by flow of pressure medium therethrough, a cylinder, a piston displaceable in said cylinder, said piston and cylinder cooperating with said valve means for actuating the same with the aid of pressure medium flowing along said flow path, said cylinder communicating with said flow path through said valve means at two locations of said flow path, and insert means located in said flow path between said two locations thereof for producing a pressure difference between said two locations.

2. Pressure medium drive according to claim 1 wherein said insert means for producing a pressure difference between said two locations of said flow path comprises a member traversible by the pressure medium and offering resistance to the flow of pressure medium therethrough.

3. Pressure medium drive according to claim 2 wherein said member has a throttling bore formed therein, said throttling bore forming part of said pressure medium flow path.

4. Pressure medium drive according to claim 2 wherein said valve means comprises a valve plate secured to said piston and displaceable into engagement with a valve seat, said member that offers resistance to pressure medium flow bein located down stream of said valve plate in the direction 0 pressure medium flow along said flow path.

5. Pressure medium drive according to claim I wherein said insert means comprises a spring-biased piston forming a throttling station in the path of flow of the pressure medium, said throttling station offering resistance to flow of the pressure medium.

6. Pressure medium drive according to claim 5 wherein said spring-biased piston forms a control slider for the pressure medium serving to actuate the valve.

7. Pressure medium drive according to claim 6 wherein said spring-biased piston is substantially rotationally symmetrical and is provided with a throttling bore extending therethrough and an annular groove formed on the outer surface thereof, both said throttling bore and said annular groove having axes substantially coinciding with the axis of symmetry of said spring-biased piston.

8. Pressure medium drive according to claim I further comprising a nozzle member having a nozzle passage ofdecreasing cross section, said nozzle member being formed in the portion thereof of substantially smallest diameter with radially extending bores, said end portion of subtantially smallest diameter being connected to said cylinder.

9. Pressure medium drive according to claim I wherein said piston acts as a differential piston.

10. Pressure medium drive according to claim 1 including a control valve communicating with said valve means actuable by the pressure medium flowing along said flow path. 

